I'm sure some of you noticed our statement on sending messages to other stars. Some of you may be surprised at our stance. We put out our statement because the SETI Institute has been indicating that they want to start transmitting. They had a workshop at the SETI Institute yesterday (Berkeley wasn't invited) where according to the Guardian, opponents of transmitting were called "paranoid." But that's the Guardian, so who knows what was really said. But here's why I think transmitting is a mistake with more detail than the statement. This is not necessarily the view of the other people who signed, or the UC.

Nobody elected us. I'm a scientist. I don't have the right to speak for the people of Earth even though I have access to a telescope that could. Same goes for any group of scientists. There's even a Declaration of Priciples that SETI scientists supposedly adhere to that says I won't transmit a message in response to a signal without global agreement. The representatives of the people of the world (the UN General Assembly) need to set the rules.

The proposal ignores that human civilization changes over time. If we are broadcasting signals that could be returned in 1200 years, we will not be the same civilization in 1200 years. According to the Guardian, at the meeting, one of the proponents said "a civilization only three hundred years ahead of ours could detect Earth’s TV signals at a distance of 500 light years." If that's the case, won't we know through other means if there is a technological civilization around the stars they target long before our signals even arrive there?

Nobody will be listening for a response. 1200 years ago, the Caliphate was at its maximum, and Muslim scholars were deriving algebra based on Hindu texts. Charlemagne was Emperor of the West. The Chinese were inventing printing using wooden blocks. Matches had not yet been invented in Europe. There was a civilization in North America that extended from Wisconsin to Florida. And we wouldn't be able to understand someone speaking English, nor would they understand us. Europeans wouldn't discover the New World for another 700 years. Regardless we will have long forgotten the SETI Institute and the signals they sent. We may be extinct, civilization may just be a memory, or we may be colonizing space. But nobody will be listening in any case.

It's impossible to do a cost benefit analysis. Nobody can tell you the probability that these signal will be detected, or if they are, what the reaction of extraterrestrials will be. Is there a 1 in a million chance that ET will decide we're a threat and eliminate us? Is there a 1 in a million chance that ET will call off colonizing the Earth when they receive a signal from us? There is no way to determine this. ET could be just like us (which would be frightening) or so different that we don't even recognize each other as intelligent (which would be frightening).

In a comparison risk analysis, suppose a 10km asteroid were going to pass through the Earth's atmosphere, igniting fires that would kill a million people. We could divert it, but there would be a 1% chance it would hit the earth destroying all life. Which choice do you make? There are ways to decide based on projected outcome and the probabilities. No such analysis can be done for METI.

The future doesn't get a vote. How many people will live in the next 1200 years? We can't consult them. Proponents seem consoled by the idea that any bad outcome won't occur in our lifetimes. If a bad outcome were to occur, those living at the time might not be so consoled by the fact that it didn't happen to us.

The signals that proponents claim we've already sent (TV, radio, Arecibo radar) are not nearly as likely to be detected as they claim. We couldn't even detect TV and radio signal at the nearest star with Arecibo. The Arecibo Planetary Radar is detectable at distances of thousands of light years, but doesn't repeatedly target the same spots on the sky. Someone receiving a single pulse is likely to discount it because it isn't repeatable.

Congratulations Eric, a carefully worded and thought out statement, which highlights a number of issues.

Firstly, that Seti@home isn't the Seti Institute, although a fair proportion of the public seem to think that they are one and the same. They seem to regard themselves as the earth's spokespeople for SETI and us as hanging onto their coat tails. The fact that Seti@home wasn't invited to the workshop seems to bear that out.

Secondly, in terms of the representatives of the people of the world, yes in theory it should be the UN General Assembly, I wonder if it is in practice? It ET were to make contact and say classically "Take me to your leader" It could well be that the UN run around like headless chickens not knowing what to do next. If they are to be earth's spokesperson, they need to have a committee set up with politicians and scientists with an internationally agreed mandate.

Thirdly, I agree that sending out signals is fraught with difficulties and needs a multilateral approach not a unilateral one. I agree your view that no for now, but leaving all options open.

Finally, I am greatly impressed that a scientist of your reputation and standing, is prepared to make a point in relation to the Guardian's style of reporting. Many of us have long held that view.

As one of the most ardent supporters of both Eric and this project...
I would like just to point out one interesting dichotomy.....with no disrespect whatsoever.

I appreciate and agree with Eric's points on whether mankind on earth should send signals abroad to entice communications with other worlds. I am not sure we should, as I believe we are approaching this with the mindset that in the universe, if there are other civilizations, we are probably the children...the most primitive of them that exist.

And yet both he and I have invested a good portion of our lives investing time, money, and effort in the Seti project which hopes to contact other intelligent life that has DONE what he proposes we should not do.

Just an interesting conflict, eh?A day without cats is like a day without sunshine.
I speak meow, do you?

My only comment is that the future has never had a vote in any way shape or form. We're leaving the future an environmental mess and they didn't get to vote about it. If we keep going the way we are this whole METI issue might be just a mute point given the time scales you mentioned. But I suspect the current push for METI probably has a short term commercial gain behind it, I guess time will tell how this unfolds.

I hope S&H does eventually discover a signal but given the time scales and distances it might just get filed away in the history books as 'We are not alone' or we may never hear anything and the history books will say 'Yep, looks like we're alone'

*The future doesn't get a vote. How many people will live in the next 1200 years? We can't consult them. Proponents seem consoled by the idea that any bad outcome won't occur in our lifetimes. If a bad outcome were to occur, those living at the time might not be so consoled by the fact that it didn't happen to us.

Double edged argument. They can blame us for not to prepare ground for contact before and prevent them from receiving the answer. Future has no vote in this case too.

In a comparison risk analysis, suppose a 10km asteroid were going to pass through the Earth's atmosphere, igniting fires that would kill a million people. We could divert it, but there would be a 1% chance it would hit the earth destroying all life. Which choice do you make? There are ways to decide based on projected outcome and the probabilities. No such analysis can be done for METI.

I would elaborate on example to make it more relevant to METI.
What if one can not be sure that asteroid pass through doing minimal damage? You suppose it as definitely known. So "safe low risk" state exists. But actually it can be not the case. Which choice then?

*The proposal ignores that human civilization changes over time. If we are broadcasting signals that could be returned in 1200 years, we will not be the same civilization in 1200 years. According to the Guardian, at the meeting, one of the proponents said "a civilization only three hundred years ahead of ours could detect Earth’s TV signals at a distance of 500 light years." If that's the case, won't we know through other means if there is a technological civilization around the stars they target long before our signals even arrive there?

*Nobody will be listening for a response. 1200 years ago, the Caliphate was at its maximum, and Muslim scholars were deriving algebra based on Hindu texts. Charlemagne was Emperor of the West. The Chinese were inventing printing using wooden blocks. Matches had not yet been invented in Europe. There was a civilization in North America that extended from Wisconsin to Florida. And we wouldn't be able to understand someone speaking English, nor would they understand us. Europeans wouldn't discover the New World for another 700 years. Regardless we will have long forgotten the SETI Institute and the signals they sent. We may be extinct, civilization may just be a memory, or we may be colonizing space. But nobody will be listening in any case.

Well, future can not change the past (at least as we think now) but past/today definitely can change the future. So it depends how you (metaphorically saying ) will rise your children. If they will continue search there will be the ones who listen. All in our hands in this sense. But we can not say the same regarding future generations. They will not be able to influence on our decision to leave them w/o Contact.

Alerting alien intelligence to our presence is not to be considered lightly, as the outcome cannot be known at present, therefore a "paranoid" tactical approach does make sense.

If any reply is to be expected during the lifetime of those who vote, it makes sense to vote on it, not arbitrarily go over the heads of many who would not embrace the idea.
On the other hand, what's the point of voting on the unknown? Do we have any idea of who we are contacting?

Unless a next-generation spectrometer identifies CFC's or other industrial componds in the atmosphere of a potentially habitable nearby planet, contact should not be expected within our lifetime, and therefore we may decide for a future generation which would oppose active SETI efforts.

Do we have any idea of who we are contacting?
How about a practical approach? What if life on Earth were threatened by something major, like geomagnetic field failure or the Sun finishing main sequence?
From a time and resource standpoint, there are a number reasons why it makes sense for an advanced technological civilization to leave its home system in generational ships, carrying as many individuals and biological samples.

I would venture as far as to say it's more economically feasible to build a large spaceship and send it to a relatively nearby system than to terraform
Venus or Mars. And with an advanced form of ion propulsion it would roughly take the same time.

We are very lucky with our star system; an advanced alien civilization may not be. Detecting us may be a lucky break for them, it may provide a golden candidate for colonization.

Not only I oppose active search. I think it even makes sense upgrading civilian and military radio broadcast regulations in order to limit transmission power and make detection as difficult as possible, something on the order of "virtual radio silence for an Arecibo-class telescope x light-years away".

Even something on the order of making illegal any non-laser satellite uplink.

*The signals that proponents claim we've already sent (TV, radio, Arecibo radar) are not nearly as likely to be detected as they claim. We couldn't even detect TV and radio signal at the nearest star with Arecibo. The Arecibo Planetary Radar is detectable at distances of thousands of light years, but doesn't repeatedly target the same spots on the sky. Someone receiving a single pulse is likely to discount it because it isn't repeatable.

A technical question if I may. You have stated the Arecibo Planetary Radar is detectable out to a distance of thousands of light years. You have assumed that if ET is listening that he will ignore the signal because it only occurs once. The question is, if ET has a different assumption, such as looking for a particular type of signal, such as sinusoidal narrow band stable carrier frequency, could ET determine that the Arecibo Planetary Radar was not generated by nature even with a single detection? You can assume ET knows more about the universe; enough to know the type of signal he is looking for cannot be created naturally, but ET can’t change the interstellar medium if it destroys the signal properties.

If we do send out signals, letting all know where we are, I hope the receivers are not human. Our water, oil and other resources would be so tempting for them, I doubt us earthlings would survive. (my one cents worth)

If we do send out signals, letting all know where we are, I hope the receivers are not human. Our water, oil and other resources would be so tempting for them, I doubt us earthlings would survive. (my one cents worth)

Any such resource would be tempting to use strictly on site, transporting them to their homeworld wouldn't make sense. Colonization would be the only thing to fear from advanced aliens.

So, I've decided that I disagree with the notion of delaying the transmission of messages.

First, I don't think that we need the UN to represent humanity in this sense. The people thinking about sending messages are smart, and presumably will include the necessary context of who we are and where we've been.

Assuming that a receiver has half a wit, they'll understand that cultures exist on different levels at different times and that what they'd find locally on reaching us would be vastly different from what existed when the messages were sent.

Second, I think this notion that no one will be listening in a thousand years is ill-conceived. We don't know that they won't be listening. Basic belief patterns have been kept largely intact in various religions for millenia. The notion that a group of people excited by the notion that we're not alone would keep the torch going with ever-more-capable technology suggests to me that not only will people be listening for an answer in a thousand years, but they'll be listening far more comprehensively than is possible today - even if it's a small subset of the populace, just as it is today.

My thought is that it's entirely possible that the risk will be that our messages that we send now are obviated by more capable and far-ranging attempts. Consider that we don't in fact understand the underlying mechanisms behind gravity. We can observe but not explain spooky action at a distance.

This all suggests to me that it's possible that we'll garner more insights into that level of physical reality as time passes, and those insights might allow us to look, listen, and communicate in ways we frankly can't imagine today, just as a thousand years ago folks might tend to burn you on a stake if you insisted too vigorously that we'd walk on the moon, send our words across the globe instantly, or cure disease by eating small claylike lumps called antibiotics.